It has been acknowledged through sociobiological research that women seek men who will provide good genes to produce strong healthy offspring, and men seek women who are attractive, because these women are seen to be most suitable for producing fit children. According to the author in last two centuries, in western societies, mate selection has also frequently led to marriage. If the man fails to meet these genetic standards, women may be driven to have extramarital affairs so that they can obtain good genetic stock, but will still keep their husband if he provides good support resources for her and her children.